一いち億おく

い

ち

お

く

Meanings

one hundred million; 100,000,000

The Japanese unit for 10^8; used in counting large numbers, especially money, population, and statistics.

一いち億おく円えんone hundred million yen (a very large sum of money)
彼かれは宝たからくじで一いち億おく円えん当あたった。
He won a hundred million yen in the lottery.
一いち億おく人にんa hundred million people (used for large populations)
日本にほんの人じん口こうは一いち億おく人にんを超こえている。
Japan's population exceeds one hundred million.
一いち億おく分ぶんの一いちone in a hundred million (an extremely small probability)
そんな偶ぐう然ぜんが起おきる確かく率りつは一いち億おく分ぶんの一いちだ。
The odds of such a coincidence happening are one in a hundred million.

十じゅう億おく
一億 is 100,000,000, exactly one tenth of 十億 (1,000,000,000), and both are built from the same 億 unit.
百ひゃく億おく
一億 is one hundred million, one hundredth the size of 百億 (ten billion).

１いち万まん
一万 is 10,000, while 一億 is 100,000,000 — learners sometimes mix up the scale between the two large-number terms.
一いっ兆ちょう
一兆 is one trillion (10^12), ten thousand times larger than 一億, so the two are easy to confuse when reading big statistics.

一いち億おく
Standard kanji spelling; high frequency in news and everyday contexts.
１いち億おく
Common in financial, statistical, or informal writing where numerals are preferred.

Compound of 一 (one) and 億 (the unit for 10^8). The unit 億 has been used in Japanese since ancient times, originally borrowed from Chinese.